The impact of floatation therapy on body image and anxiety in anorexia nervosa: a randomised clinical efficacy trial

Abstract

Body image disturbance and anxiety are core features of anorexia nervosa (AN), a psychiatric disorder with one of the highest mortality rates. This study examined the efficacy of a novel non-pharmacological treatment, floatation-REST (Reduced Environmental Stimulation Therapy) on body image disturbance and anxiety in inpatients with AN. This parallel group randomised controlled trial compared floatation-REST vs. care as usual in women and girls hospitalised for treatment of AN in Tulsa, Oklahoma, USA. Participants were randomised on a 2:1 ratio to receive eight, twice-weekly, 60-min floatation-REST sessions for 4 weeks, in addition to care as usual, or to receive care as usual. The primary outcome was the average change in body dissatisfaction from pre- to post-float as measured by the Photographic FigureRating Scale. The secondary outcome was the average change in anxiety from pre- to post-float as measured by the state version of the State Trait Anxiety Inventory. Longitudinal effects of floatation-REST on body dissatisfaction were also examined. All analyses were conducted using the intention-to-treat principle. Planned linear mixed models tested the effect of floatation-REST vs. care as usual. The trial was preregistered (clinicaltrials.govNCT03610451). Between March 16, 2018 and February 25, 2021, 133 participants were screened for eligibility, and 86 were consented. Eighteen were excluded after consent, for a final randomisation sample of 68 participants (45 floatation-REST; 23 care as usual). There were two session by condition interactions on body dissatisfaction (p=0.00026) and state anxiety (p<0.0001), such that the floatation-REST group exhibited acute (i.e., pre- to post-session) reductions in body dissatisfaction (floatation-REST group mean change (Δm)=-0.43; 95% CI-0.56 to-0.30, p<0.0001, Cohen's d=0.23), and acute reductions in anxiety (floatation-REST group Δm=-15.75; 95% CI-17.95 to-13.56, p<0.0001, Cohen's d=1.52); however, the care as usual group exhibited no significant changes. With regard to longitudinal results, there was a significant time by treatment interaction between baseline and immediately post intervention (p=0.012) and baseline and six-month follow up (p=0.0019). At immediately post intervention, there was a trending reduction in body dissatisfaction for the floatation-REST group (Δm=-0.41, 95% CI-0.86 to 0.03, p=0.068) and care as usual group (Δm=0.61; 95% CI-0.04 to 1.27, p=0.070). At six-months post-intervention, the floatation-REST group exhibited lower body dissatisfaction (Δm=-0.91; 95% CI-1.37 to-0.45, p=0.0020, Cohen's d=0.53) whereas the care as usual group reported no change in body dissatisfaction (Δm=0.35; 95% CI-0.28 to 0.98, p=0.96) relative to baseline. There were no adverse events related to the trial during the study. Our findings suggest that Floatation-REST decreased body dissatisfaction compared to care as usual acutely after each float session and at six-month follow-up. Floatation-REST has potential utility for the treatment of body image disturbance and anxiety in AN. These results may be limited by some generalisability concerns given the recruitment of a modest sample receiving inpatient treatment at a single site. The William K. Warren Foundation.